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Water Pump Replacement
I need to replace my water pumps and the original pump is no longer available. I emailed Marathon to find out the current water pump brand and model being used but they never returned an answer. No response sounds like their almost standard response where they want me to come into their shop for a replacement. (That said, I love my Marathon)
The situation is that both pumps were replaced recently. However, when not hooked up to city water, you can hear the pump pulsating and it’s loud…something I never heard before and very annoying. From the salon to the bedroom you hear a loud ruurh, ruurh, ruurh, ruurh whenever the water is running. And the water pressure is constantly dropping which coincides with the pump noise…heavy pressure when the pump runs to a lighter pressure when the pump is relaxing. So evident to watch the drop in water pressure from both the water faucets and shower. Not like the original setup at all.
Pump replacement facility said new pumps had same GPM as the original pumps. In my travels, I had another repair facility try to rectify the situation and they said the pumps were not big enough to handle the load. Both facilities have excellent reputations with Prevost owners.
If anyone with a later model Marathon could give me their water pump models it would certainly be appreciated.
Or if there is an adjustment I can make that repair facility #2 didn’t know about, I’ll give that a whirl.
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35 Replies
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Don’t know what your original was Jimmy, mine has a Headhunter. All I can tell you is the pressure remains at 45 psi no matter how many faucets are on and does not short cycle. We can usually get 2 glasses of water out of the fridge before the pump comes on, the expansion tank does it’s job well.
I understand later model Marathons had two small pumps instead of one big one like mine.
Tradewinds Coach
Kyle Bennett (Service)
Brian Miller (Sales) -
We have 2016 Marathon in the shop. I’ll check it out tomorrow and let you know what it has Jimmy.
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I know that Marathon started putting on two 12v pumps instead of the 110v pump, but I thought that was more recent than 2006.
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If your pump is 110v Grundfos, the Walrus brand TS-800 is almost plug and play and many hundreds of dollars cheaper than the Grundfos MQ-45. Just google residential booster pump.
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Freshwatersystems.com has the Grundfos MQ-45 for $492.39 and free shipping.
I replaced our original MQ-45 in 2011 with the same model and it has done well so far.
We use the Grundfos over city water almost exclusively, as we prefer to fill the tank through our Doulton Ceramic water filters. The pressure drop is usually to great to operate with the filters installed.
I do keep a new in the box replacement 12v pump on board.
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Jimmy,
Rapid cycling is often related to leaks, either in the system downstream from the pump or at the pump itself. It could also be a problem with the accumulator tank but less likely. Check for leaks before spending the big bucks. Good Luck!
Doug
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Short cycling in my experience has been associated with a waterlogged accumulator tank bladder or lack of the correct pressure or a leaking check valve that allows pressurized water downstream from the pump to leak back into the water tank via the pump.
Thank goodness none of the short cycling issues I have encountered are leak related because a pump that is short cycling is delivering a lot of water through the leak and into a coach or bay.
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Jimmy,
You said you are experiencing low pressure and short cycling after having the new pumps installed. It sounds to me like the new pumps are set at a lower pressure and the bladder tank was not reset to that lower pressure. If the bladder tank air pressure is higher than the pump cut in pressure the tank cannot do its job and the pumps could short cycle. I think the pressure switches need to be turned up to the original pump pressures and the bladder tank checked for proper precharge.
Another possibility: Were any check valves added to the system? A check valve must be installed in a location that ensures a constant open line from the pressure switch to the bladder tank. For example, if a check valve is installed after the pump and the pressure switch is inside the pump, the pressure switch is isolated from the bladder tank upon pump shut off. This could cause short cycling.
The second scenario is a long shot but I have seen devices placed where they should not be. A screen or filter placed in the wrong location can do the same thing.
I would check the pump and bladder pressures first!
Jeff
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Sorry, I should have posted this earlier. I think we have the issue resolved.
Immediately after I posted the original message, I received an unsolicited call from Kyle at Tradewinds. After a few questions and tests, it was determined I had a bad accumulator tank. Where air should have been releasing I got nothing but water. Hence, the accumulator tank looks like it needs replacing. Thanks Kyle.
So, I was misinformed by the other Prevost repair facility that said the pumps were not powerful enough.
I went from my Buffalo, NY garage directly to Florida where I have city water hooked up with great pressure, so no immediate need to use the 2 water pumps. Now that the holidays are nearly over, I’ll be replacing the accumulator tank.
Thank you all for your input.
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Great Jimmy! The great one nails another one with the water logged tank diagnosis. Heres hoping they didnt replace your original pumps for what was a tank issue. Thanks for the update.
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The replacement pumps were warranted. Both 10 year old pumps were completely frozen up probably from not getting any exercise since I’m always on city water with high pressure. I’ve learned from Tradewinds to exercise each of the two pumps at least once a month now.
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That is a DC pump and replacing it you have two choices if you stick with DC power. Rebuild or replace it which is by far the best option, or go with something like a Shurflo or equivalent. If you go with the second option you have to get into dealing with an accumulator tank to enable the Headhunter toilet to continue to function.
A third choice would be to use a Headhunter pump but then you have to determine where you will get 120V AC power (such as robbing it from the bay heater) and how you will control it from inside the coach.
Free advice……..bite the bullet and stick with the Groco.
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I too have that Groco and will stick with it, if it ever messes with me. No biting required.
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I will take the advice and stick with this type pump .
Thanks everyone
Darrell
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I had one fail on my last coach and I scoured the internet trying to do better than the $2400 price. I was able to find a brand new one for $1000 on ebay so it might be possible to save serious money by spending some time looking for one.
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